Gas-activated and gas-depolarized deferred action cell



July 12, 1960 R. E. JOHNSON ET AL 2,945,079

GAS-ACTIVATED AND GAS-DEPOLARIZED DEFERRED ACTION CELL Filed June 19,1957 jaw ly; ,{V R42 34 2 i #fif- '6 n 30 i v Ac1ivaror& DepolarizerContainpn 20 L g 2 r I m g 11.1 1

i3 Steel Base I Carbon Conducting Coating (Cathode Collecior) WaterProofed Diffuser Converter Layer Hydrated Sah & Paper Fiber SeparaiorZinc Anode RICHARD E. JOHNSON NELSON C. CAHOON HUGH E SCHAEFER 3%?ATTORNEY nitedj S ars-s Pe m i GAS-ACTIVATED AND GAS-DEPOLARIZEDDEFERRED ACTION CELL Filed June 19, 1957, Ser. No. 666,730

4 Claims. (Cl. 136-90) This invention relates to chlorine-depolarized,deferred action cells wherein a gas is used to release water fromhydrated inorganic salts to moisten an electrolyte-separator member andproduce electrical energy.

The major problems encountered with gas-activated deferred action cellsheretofore proposed are centered around the attainment of minimum cellthickness to provide the maximum possible energy-density because of theneed for a quantity of oxidic depolarizer, the rapid entry of activatinggas without adversely affecting moisture retention, the prevention of,conductive bridges, and the design of cell containers to permiteflici'ent storage, retention, and release of the activating gases.

The main object of this invention is to provide a gasdepolarized,gas-activated deferred action battery system capable of instantactivation at low temperatures, and

capable of producing highlcurrents quickly at low temperatures.

. An important object of the invention is' to provide a gas-depolarizeddeferred action cell wherein a gas is used to release water of hydrationfrom hydrated salts incorporated in separator means.

. These and other objects are achieved by the invention which will bedescribed with reference to'the accompanying drawing in which:

v Fig. l is a vertical section of a battery of cells embodying theinvention and housed in an enclosed container; 1 Fig. 2 is an enlargedvertical section of a portion of a cell embodying the invention of thetype used in the battery of Fig. 1, showing in detail the novelseparatordis closed herein. I

The cell ofthe invention comprises a consumable metal anode; a gaseousdepolarizer; an activating gas and depolarizing gas container, aseparator adjacent to the anode and containing materials which reactwith activating gas to provide ionically conductive electrolyte, anelectronically conductive converter which also functions as cathodecurrent'collector, and an electronically conductiveelectrolyte-non-wettable diffuser element adjacent to said cathodecurrent collector and'capable of providing a path for activating gas tosaid separator. j

Referring particularly to Figs. 1 and 2 of the drawing, the cell of theinvention may comprise a zinc anode to one side of which may be applieda steel supporting member 13 coated with a conductive layer of carbon 12to serve as the cathode collector. Adjacent to the other side of thezinc anode 10 is a dry separator 14. This separatorcontains hydratedsalts hereinafter described with greater particularity. Adjacent to theseparator 14 is a converter 1? in contact with a diffuser element 16fabricated of conductive carbon coated paper or other conductive fibers.The cell is completed by the conducting carbon coating 12 applied to thesurface of the steel base.

As indicated in Fig. 1, the cell elements just described may be annular.in that figure for purposes of illustration, are arranged in seriescontact to form a battery and a metal ampule 18 A number of cells, fourbeing shown 2,945,019 Patented July 12, 1960 containing compressedactivating gas and compressed depolarizing gas to be describedhereinafter, and provided with a frangible diaphragm 20, is placedwithin the central aperture of the annular cell elements. The

ampule 18 is provided with an insulating sheath Z2 suit- 20 of theampule 18 when it is desired to activate the battery. Appropriatepositive 32 and negative 34 leads are provided from the battery toexternal terminals 36 and 38, respectively.

In the cell of the invention the anode may be formed of any of a numberof metals. Among those which are satisfactory are aluminum, magnesium,cadmium, manganese and iron, in addition to zinc. Economicconsiderations make zinc the most desirable of these. Similarly, any ofa number of depolarizing gases may be used. Halogens such as bromine,chlorine, and fluorine are conventional depolarizing gases. Of these,chlorine is preferred.

The novel separator utilized in the cell of the invention containsfinely divided crystals of an inorganic hydrated sa-lt combined with asuificient amount of inert fibrous materials such as alpha celluloseflock, glass flock, polyethylene fibers or vinyl fibers to support thecrystals and to permithandling. Typical inorganic salts include hydratedhydroxides of the alkali metals and alkaline earth metals such as of apreferred method of preparing the separator the following is given: 30grams of crystalline and 1 gram of glass fiber were ball milled with 200cc. of a saturated aqueous solution of Sr(OH) Ball milling was continueduntil the salt particles were reduced in size so as to pass a 200 meshscreen. When the mixture attained the indicated physical state, it waspossible to cast'it or to calender it using, for example, as desired, aFourdrinier engine. The formed mass next was dried in an oven at about65 C. to remove excess water and cause the salt to assume the hydrationrepresented by the formula Sr(OH) -8H O. The separator so pro- 1 ducedcontains about percent by weight of hydrated salt.

The present cell is intended to be depolarized by a depolarizing gassuch as chlorine placed in the activatordepol-arizer ampule. Thedepolarizing gas is rendered active by a converter element such asactivated carbon black. At low temperatures, where the vapor pressure ofchlorine is not sufiicient for good depolarization and high batteryperformance, heat supplied by the coordination reaction of ER, with thehydrated salt forming material of the separator increases thetemperature of the system to such a level that the vapor pressure ofchloline is sufiicient for high battery output. This is not the case forthe ordinary chlorine depolarized cell, and is one of the importantadvantages of the present novel system.

In cells embodying the invention utilizing a dry separator andelectrodes of the type described, the diffuser element may be composedof any convenient gaspermeable material such "as a porous ceramicmaterial, v r

" "a wet'eleetrolyte. As'a"res'1'1lt,'the shelf life of'such' cellsporous carbonmaterialffibrous paper or textile materials which willpermit ready access of such gas to the separator and its containedelectrolyte-forming rnaterial. 'fI'his'ifead'y' accessofigasis'rnaintained by watergpr'o ofing the difiuserielement. Thediffuser element must also be electronically conductive. For convenienceeconomy, ordinary blotting pa er is satisfactoryfor use as a diflnserelementvvhen rendered conductive. A preferred difius'er'isthatdescribedand claimed in the application '1956, and'now abandoned.

The dilfuser element is'placed in the cell adjacent, to the converter,ivhichin' turn is in contact with thediffuser, andthece-ll is completedbyplacing a duplexelec- 'trode 'vvith its carbon "cathode currentcollector surface adjacent to the other surface of the diffuser element.

The cell of the invention may be activated'by'late'r'al -difius'ion ofactivating" gas fromthe depolarizingfgascontaining reservoir 18 throughthe difiuser' element- If desired, a'separa'te' container may beprovidedforithe activating gas. In either case, theactivating gas.coordinates with the electrolyte-forming material'to produce ionicallyconductive electrolyte. The activating gas 'reacts with the hydratingsalt to release Water .of hydrat'iontherefro'rn, which reacts withadditional boron trifluoride -to form-hydrogen fluoride andboric'acidfhydrogen fluoride serving as electrolyte;orby'forming'nuoboric-acid by'reacti'on With'the boric acidgin whichcase lil'uoboric'acid serves asthe electrolyte. During thesereactions'the separator element is Wet by the released Water ofhydration. 'Reactions whichare believed to summarize the'pheno'menawhich take place in' the cell are setforth below:

3[Sr(OH) -8H O]+10BF a a Suitable activating gases in addition to borontrifluoride are silicon tetrafluoride, hydrogen chloride and hy-'drogen" fluoride. The cells of the inventionmay also be activated byusing an excess of certain depolarizing gases, preferably chlorine.In'this embodimentthe amount of depolarizing gas placed inthe ampule'isincreased over and above that needed'for depolarizing purposes.

A cell of this type operates as follows: Activating gas BF or others)"entersthe porous dry separator and releases water of hydration from anelectrolyte-former in the=separaton "The water and activating gas orsaltsof the separator combine to form an ionically conductingelectrolyte which wets the' surface of the electronically conductiveconverter layer, and the anode. Depolarizing 'gas -(chlorine or others)enters the "electronically conducting 'gas-pern1eable difluser, passesthrough the 'converter'layer where it"is converted into an active"depolarizinggas' anddepolarizes the cell at theconverterelectr'olyteinterface. A conducting carbon coating on the otherside of the diffuser layer serves to complete the cell by collec'tingFthe electron current 'which has been passed to-it by-the conductivediffuser andconverter. This conducting'cathode collector maybeconveniently mechanically-supported by a steel base strip, which turnmay be contacting the anode layer of an adjacent cell inseries connectedbattery stacks, or maybe coated "with a carboncathode collecting layerof an adjacent "parallel connected cell.

Conventional chlorine-depolarized cells normally use is unreliable, forthe electrolyte dries out in a period of time, depending upon storageconditions. In addition, the water often migrates to unwanted places inthe cell. Again the activation oft'su'ch" cells is slow and unreliableat lowtemperatures. By contrastin the cell of the inventionfbeingactivatedbya gasthasfan indefinite shelf life, andtemperaturesof'storage or of activation are not -a?factor.

Prior art gas P: activated cells #so 'far have: used oxidicdepolarize'rsi By -n'sin'g gasdepolarization,ithe cell' of the inventionfurnishes a higher current"carrying-capacity per unit volun1e.than-theformercells.

Cells made in accord with thepresentinvention suitably have a thickness'of around-35 to 40 thousandths of an inch per individual cell. Suchcells deliver current .drainsi n excess of .250.mils per inch square ofelectrode area. Thevol'tagelevel underload varies with theload.i'lheo'pen circuit voltage is 1i9"to.2.1' volts. Theactivation't'imeis'abOutM second at roolrnjtemperature. The cellsof theinvention operate'at -'"40.F.

-"Whatis claimed is:

' 1."A' deferfedaction'battery comprising -a container and in'saidfcontainer a frangible ampule containing activating" anddepolarizing gases, means for fracturingsaid ameulefat .leastfone'cellnnit comprising a metallic base and on said base aconductivecarboncoating, "an electron ally conductive'watebproofed diffuser adjacentsaid coating in"contacftherewith, an electronically conductive converterlayer "ailjacent to said'ditfuseriin contact therewith, adryi fibrousgas-permeable separator in con- ;tact yvithsaid converter layer, andconsisting of "finely dividedi'cry'stals' bf anin'organic hydratedsalfof ametal sele'cte dd'rom' thegtonp consisting of the alkali metalsand-the alkaline earthmetals, said crystals beingsup- 'po'r'tedhy meansof an'ine'rt fibrousfmaterial, 'said1crys talsjv providing wa er andelec trolyte upon reaction with activating"gas;"and' a' consum lbleanode in' contact with said separator. v g f2. Afgas depolarizedgasactivatable deferred action cell comprising "a container, and in.said. container an anode of a consumable metalselecte'd from the groupconsisting :er zinc, nickel, cadmium, lead, aluminum,

riran,"'manganese andmag'nesium, a frangible ampule containing "amixture" of activating gas with depolarizing gas;,adr'y'fib'rousseparator permeable to gas and containing hydrated material adapted toprovide water and electrolyte upon reaction with saidactivating gas, andmeans providing access for said; gas to said electrolyte-forming"material's. g 3.',The"cell of claimlwherein said depolarizing gas is:selected from the group consisting of chlorine, bromine and lliiorine,andsaid activating gas is selected from the group consisting ofbor'ontrifluoride, silicon tetrafinoride, hjdr dgen chloride and mixturesthereof. 7 v

"4.The c'ell'o'f claim'ITWherein saidv cell is depolarized byfchlo'rine'gas andiactivated by an excess of theLsame References Cited in the fileof this patent .UNITED STATES PATENTS 'Hatfield tom. 28, 1952 j Gold'Feb."26, 1957

1. A DEFERRED ACTION BATTERY COMPRISING A CONTAINER AND IN SAIDCONTAINER A FRANGIBLE AMPULE CONTAINING ACTIVATING AND DEPOLARIZINGGASES, MEANS FOR FRACTURING SAID AMPULE, AT LEAST ONE CELL UNITCOMPRISING A METALLIC BASE AND ON SAID BASE A CONDUCTIVE CARBON COATING,AN ELECTRONICALLY CONDUCTIVE WATER-PROOFED DIFFUSER ADJACENT SAIDCOATING IN CONTACT THEREWITH, AND ELECTRONICALLY CONDUCTIVE CONVERTERLAYER ADJACENT TO SAID DIFFUSER IN CONTACT THEREWITH, A DRY FIBROUSGAS-PERMEABLE SEPARATOR IN CONTACT WITH SAID CONVERTER LAYER, ANDCONSISTING OF FINELY DIVIDED CRYSTALS OF A INORGANIC HYDRATED SALT OF AMETAL SELECTED FROM THE GROUP CONSISTING OF THE ALKALI METALS AND THEALKALINE EARTH METALS, SAID CRYSTALS BEING SUPPORTED BY MEANS OF ANINERT FIBROUS MATERIAL, SAID CRYSTALS PROVIDING WATER AND ELECTROLYTEUPON REACTION WITH ACTIVATING GAS, AND A CONSUMABLE ANODE IN CONTACTWITH SAID SEPARATOR.